My son is nearly 4 years old and past few days he is coughing heavily during night times and in early morning .He becomes normal after 8 am .Once sun is out .We are already giving him. levokast kid tablet, Clariwin, Telekast. Is there any suggestion it is hard to see him suffer this much. He is not drinking hot water and wants only cold to drink and because of that his voice is also frozen. During day time he is normal and after 8 pm he has heavy cough. Please suggest a good solution in this..